Upper structure and shoe including upper structure

ABSTRACT

An upper structure includes: an upper body including a stress relaxing portion which is elastically deformable; and a shoelace (a fastening member) attached to the upper body. The stress relaxing portion has: such stretchability that in an elastic range, the stress relaxing portion stretches to become longer when the upper body is pulled with the shoelace than an initial length of the stress relaxing portion; and stress relaxation properties with which the stress relaxing portion relaxes stress with the passage of time from a moment when the upper body is pulled, while remaining in the stretched state.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2018-057059 filed on Mar. 23, 2018, the entire disclosure of which is incorporated by reference herein.

BACKGROUND

The present disclosure relates to an upper structure and a shoe including the upper structure.

A conventional upper structure for a shoe with improved fitting properties for fitting a wearer's foot has been proposed in, for example, Japanese Patent No. 5033878.

This patent document discloses an upper structure for a shoe, the upper structure including an upper body and a stretchable fabric provided on the upper body. The stretchable fabric can be stretched at a tensile rate from 10% to 40% in the length direction of the shoe and at a tensile rate from 0% to 30% in the width direction of the shoe.

In the upper structure of Japanese Patent No. 5033878, the stretchable fabric is pulled in a predetermined direction to be fitted to a foot of each wearer. However, in the upper structure of Japanese Patent No. 5033878, the upper body might strongly tighten the foot of the wearer due to the stress generated at the time when the fabric is pulled. As a result, even if the upper body fits the shape of the wearer's foot, a problem may arise: the wearer feels uncomfortable.

In view of the foregoing background, the present disclosure attempts to improve fitting properties for conforming to differences in the shape and size of feet among individual wearers and ensure comfort of the wearers.

SUMMARY

A first aspect of the present disclosure is directed to an upper structure for a shoe. The upper structure includes: an upper body including a stress relaxing portion which is elastically deformable; and a fastening member attached to the upper body, and configured to keep the upper body fitted to a foot of a wearer when the upper body is in a pulled state in which the upper body is pulled with the fastening member. In an elastic range, the stress relaxing portion is configured to enter, when the upper body is in the pulled state, a stretched state in which the stress relaxing portion is stretched to become longer than an initial length thereof, and to relax stress with passage of time from a moment at which the upper body enters the pulled state, while remaining in the stretched state.

In the first aspect, the stress relaxing portion is configured to enter, when the upper body is in the pulled state, the stretched state in which the stress relaxing portion is stretched to become longer than its initial length in the elastic range. That is, the stress relaxing portion has stretchability. Because of this stretchability, the upper body, which includes the stress relaxing portion, is allowed to fit the shape and size of a foot of each wearer by being pulled with the fastening member. Such features exhibit fitting properties for conforming to differences in the shape and size of feet among individual wearers. In addition, the stress relaxing portion is configured to relax the stress with the passage of time from a moment at which the upper body enters the pulled state, while remaining in the stretched state. That is, the stress relaxing portion has stress relaxation properties. The stress relaxation properties can reduce the force with which the upper body strongly tightens the foot of the wearer due to the stress generated in the pulled state. As a result, even if the upper body is fitted to the foot of the wearer, comfort is ensured. Thus, the first aspect can improve fitting properties for conforming to differences in the shape and size of feet among individual wearers, and can ensure comfort.

A second aspect of the present disclosure is an embodiment of the first aspect. According to the second aspect, the upper body is configured so that, when the upper body is released from the pulled state and returns to a state before the pulled state, the stress relaxing portion is restored to a state in which the stress relaxing portion is loose and out of contact with the foot of the wearer in the elastic range.

In the second aspect, the stress relaxing portion is elastically deformable and restorable, so that the upper body can endure repeated use without losing shape.

A third aspect of the present disclosure is an embodiment of the first aspect. According to the third aspect, the stress relaxing portion is disposed in a portion of the upper body, the portion corresponding to a forefoot of the foot of the wearer.

In the third aspect, the upper body can be fitted to the forefoot of the wearer's foot.

A fourth aspect of the present disclosure is an embodiment of the first aspect. According to the fourth aspect, the stress relaxing portion is disposed in a portion of the upper body, the portion corresponding to a midfoot of the foot of the wearer.

In the fourth aspect, the upper body can be fitted to the midfoot of the wearer's foot.

A fifth aspect of the present disclosure is an embodiment of the first aspect. According to the fifth aspect, the stress relaxing portion is disposed in a portion of the upper body, the portion corresponding to a hindfoot of the foot of the wearer.

In the fifth aspect, the upper body can be fitted to the hindfoot of the wearer's foot.

A sixth aspect of the present disclosure is directed to a shoe including the upper structure of any one of the first to fifth aspect.

According to the sixth aspect, the shoe can be provided with the same advantages as those of the first to fifth aspects.

A seventh aspect of the present disclosure is an embodiment of the sixth aspect. According to the seventh aspect, the shoe further includes a sole body configured to support the foot of the wearer and fixed to a lower portion of the upper body. The fastening member is attached to an upper portion of the upper body, the stress relaxing portion continues from a fixing position at which the lower portion of the upper body and the sole body are fixed together to the upper portion of the upper body, and, is configured to stretch in a direction from a base point corresponding to the fixing position to the upper portion of the upper body when the upper body enters the pulled state.

In the seventh aspect, the stress relaxing portion stretches over a wide range from the fixing position of the lower portion of the upper body and the sole body to the upper portion of the upper body. Therefore, the upper body can be easily fitted to the foot of the wearer, improving comfort of the wearer wearing the shoes.

An eighth aspect of the present disclosure is directed to a shoe including the upper structure of the fifth aspect, wherein the upper body is configured such that the stress relaxing portion stretches in a longitudinal direction while the upper body is pulled forward with the fastening member.

In the eighth aspect, when the upper body is pulled forward with the fastening member, the stress relaxing portion extends in the longitudinal direction, so that the upper body is easily fitted to the hindfoot (particularly, the heel) of the foot of the wearer. As a result, the stability of the wearer can be improved when the wearer steps on the ground during, for example, running or walking.

As can be seen, the present disclosure can improve fitting properties for conforming to differences in the shape and size of feet among individual wearers, and ensure comfort.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a shoe according to an embodiment of the present disclosure.

FIG. 2 is a plan view showing the shoe according to the embodiment of the present disclosure, together with a skeletal structure of a foot.

FIG. 3 is a side view, as viewed from a lateral side, illustrating the shoe according to the embodiment of the present disclosure, together with the skeletal structure of the foot.

FIG. 4 is a vertical cross-sectional view illustrating a structure of an upper body.

FIG. 5 is a cross-sectional view taken along line V-V in FIG. 3.

FIG. 6 corresponds to FIG. 5 and illustrates a state in which the upper body is pulled with a shoelace.

FIG. 7 is a graph showing how a load varies with the passage of time while a predetermined amount of strain is maintained in a specimen of the stress relaxing member to which the load is applied.

FIG. 8 is a side view illustrating an upper structure according to a first variation, viewed from the lateral side.

FIG. 9 is a side view illustrating an upper structure according to a second variation, viewed from the lateral side.

FIG. 10 is a side view illustrating an upper structure according to a third variation, viewed from the lateral side.

FIG. 11 is a side view illustrating an upper structure according to a fourth variation, viewed from the lateral side.

FIG. 12 is a side view illustrating an upper structure according to a fifth variation, viewed from the lateral side.

FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. 12.

FIG. 14 corresponds to FIG. 13 and illustrates a state in which the upper body of the upper structure according to the fifth variation is pulled with the shoelace.

FIG. 15 corresponds to FIG. 3 and illustrates an upper structure according to a sixth variation.

FIG. 16 is a vertical cross-sectional view illustrating a configuration of an upper body according to another embodiment.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the following description of the embodiments is merely an example in nature, and is not intended to limit the scope, applications, or use of the present disclosure.

FIGS. 1 to 3 illustrate an upper structure 1 according to an embodiment of the present disclosure and an overall structure of a shoe S including the upper structure 1. A pair of shoes S may be used, for example, as athletic shoes for running and various sports, sneakers for daily use, or rehabilitation shoes.

The drawings illustrate a left shoe S only as an example. Since the right shoe is symmetrical to the left shoe, only the left shoe will be described in the following description, and the description of the right shoe will be omitted herein.

In the following description, the expressions “above,” “upward,” “on a/the top of,” “below,” “under,” and “downward,” represent the vertical positional relationship between respective components of the shoe S. The expressions “front,” “fore,” “forward,” “anterior,” “rear,” “hind,” “behind,” “backward,” and “posterior” represent the positional relationship in the longitudinal direction between respective components of the shoe S. The expressions “medial side” and “lateral side” represent the positional relationship in the foot width direction between respective components of the shoe S.

(Sole Body)

As illustrated in FIGS. 1 to 3, the shoe S includes a sole body 2. The sole body 2 includes an outsole 3 and a midsole 4.

The outsole 3 is provided to correspond to a region extending from a forefoot F to a hindfoot H of a foot f of a wearer. The outsole 3 is made of a hard elastic material which is harder than the material for the midsole 4. Examples of materials suitable for the outsole 3 include, but not are limited to, thermoplastic resins such as ethylene-vinyl acetate copolymer (EVA), thermosetting resins such as polyurethane (PU), and rubber materials such as butadiene rubber and chloroprene rubber.

The midsole 4 is configured to support the plantar surface of the foot f of the wearer. The midsole 4 is made of a soft elastic material. Examples of the material suitable for the midsole 4 include, but are not limited to, thermoplastic synthetic resins such as ethylene-vinyl acetate copolymer (EVA) and foams of the thermoplastic synthetic resins, thermosetting resins such as polyurethane (PU) and foams of the thermosetting resins, and rubber materials such as butadiene rubber and chloroprene rubber and foams of the rubber materials. The midsole 4 is stacked on and bonded to the upper side of the outsole 3 with an adhesive or other means.

The midsole 4 is a multilayer including an upper midsole component 5 and a lower midsole component 6 stacked below the upper midsole component 5. Between the upper and lower midsole components 5 and 6, a corrugated plate 7 is disposed at a position corresponding to a hindfoot H. The corrugated plate 7 has a corrugated shape having peaks and valleys alternating with each other in the longitudinal direction.

(Upper Body)

As illustrated in FIGS. 1 to 3, the upper structure 1 includes an upper body 10 for covering the foot f of the wearer. A lower periphery of the upper body 10 is integrally fixed to the entire periphery of the upper midsole component 5 with an adhesive or other means (see FIGS. 5 and 6).

The upper body 10 is provided with, in its upper portion, an ankle opening 11 through which the wearer inserts the foot f. Further, the upper body 10 has, in its upper portion, a throat 12 that is continuous with the ankle opening 11 and extends in the longitudinal direction. In the upper portion of the upper body 10, an eyelet trimming part 13 is fixed along the throat 12 by, for example, sewing. The eyelet trimming part 13 is made of, for example, artificial leather, and is disposed at a position corresponding to a foot instep region of the wearer's foot f. The eyelet trimming part 13 has, in its left and right edge portions, a plurality of eyelet holes 14, 14, . . . which are arranged at intervals in the longitudinal direction and pass through the eyelet trimming part 13. A tongue 15 is attached to a front edge of the throat 12 to open and close the throat 12.

Further, a shoelace 16 (a fastening member) is provided on an upper portion of the upper body 10. The wearer laces the shoelace 16 to pull the upper body 10 so that the upper body 10 is fitted to the wearer's foot f and maintained in such a fit state. The shoelace 16 is passed through the eyelet holes 14, 14, . . . that are arranged in the left and right edge portions of the eyelet trimming part 13, and attached to the upper body 10.

(Fabric Material)

As illustrated in FIGS. 4 to 6, the upper body 10 has a fabric material 21. The fabric material 21 is comprised of a stretchable material. Specifically, examples of suitable materials for the fabric material 21 include, but are not limited to, knitted fabric, woven fabric, unwoven fabric, synthetic leather, artificial leather, and natural leather.

In particular, as the fabric material 21, a mesh fabric having meshes and produced by warp-knitting (e.g., single-raschel knitting or double-raschel knitting) a polyester yarn or a polyurethane yarn may be suitably used, for example. Alternatively, the fabric material 21 is suitably comprised of a tricot fabric of a stretchable polyurethane-containing yarn. The fabric material 21 having such a configuration is characterized in that the fabric itself tends to become more flexible as the stretchability of the yarn increases, as the diameter of the yarn decreases, or as the stitches become coarser. Moreover, employing a mesh fabric (e.g., a single-raschel or double-raschel knit fabric) as the fabric material 21 allows the fabric material 21 to have an improved stretchability even if the yarn forming the mesh fabric is poorly stretchable.

On the other hand, improvement of the stretchability of the fabric material 21 can be achieved not only by means of the characteristics of the constituting materials of the fabric material 21, but also by forming the fabric material 21 to be relatively thin. Alternatively, improvement of the stretchability of the fabric material 21 can be achieved also by forming one or more slits (not shown) in the fabric material 21.

(Stress Relaxing Portion)

As illustrated in FIGS. 1 to 3, the upper body 10 has a stress relaxing portion 22 that is elastically deformable. In this embodiment, the stress relaxing portion 22 is disposed so as to correspond to a portion, of the upper body 10, extending from the forefoot F to the hindfoot H of the foot f of the wearer. As illustrated in FIGS. 4 to 6, the stress relaxing portion 22 is formed on a surface of the fabric material 21 and is exposed to the outside of the shoe S. In FIGS. 1 to 6, the stress relaxing portion 22 is marked and accentuated with dot hatching.

A non-limiting exemplary method for producing the stress relaxing portion 22 includes: hot pressing a stress relaxing member using a hot pressing machine (not shown) from the outer surface of the fabric material 21 while the stress relaxing member is pressed onto the fabric material 21; and thereafter, providing a cooling treatment to melt areas where part of the stress relaxing member has been melted and permeated the fabric material 21. As a result of this production method, the stress relaxing member is fusion bonded to the surface of the fabric material 21. Note that the thickness of the stress relaxing portion 22 after the fusion bonding is preferably, but not limited to, within a range of 0.2 mm to 2.0 mm. In other words, the stress relaxing portion 22 may be set thicker than 2.0 mm.

Examples of suitable materials for the stress relaxing member include thermoplastic elastomers. In view of the fact that the shoes S are mainly used as sport shoes, it is preferable to choose, among the thermoplastic elastomers, one having such physical properties that a value (so-called tan δ) obtained by dividing a loss elastic modulus E″ by a storage elastic modulus E′ exhibits a peak value in a range of room temperature. Note that, in this embodiment, the range of room temperature as used herein refers to a temperature range in an atmospheric environment in which various athletic games are played. Specifically, the range of room temperature within which the tan δ reaches the peak value is preferably equal to or higher than 0° C. and lower than 40° C.

It is generally said that a temperature corresponding to the peak value of tan δ is a glass transition point Tg. The glass transition point Tg has been known to influence the temperature dependence and the rate dependence of a resin material. A thermoplastic elastomer, which possesses such physical properties that the tan δ described above exhibits the peak value in the range of room temperature, has its glass transition point Tg in the range of room temperature, and becomes more likely to exhibit the rate dependence as the viscosity (loss elastic modulus E″) increases and/or the elasticity (storage elastic modulus E′) decreases in the range of room temperature.

Specifically, a thermoplastic elastomer comprised of a composition containing a 4-methyl-1-pentene α-olefin copolymer (manufactured by Mitsui Chemicals, Inc.) is suitably used as a material for the stress relaxing member. A thermoplastic elastomer containing this composition or any other similar composition can be configured such that the tan δ reaches the peak value in the range of room temperature and the hardness of the thermoplastic elastomer has a practical value suitable for this embodiment, by adjusting the blend amount of an olefin polymer component such as polypropylene (PP) and the blend amount of an olefin rubber component such as ethylene propylene rubber (EPR) and ethylene propylene diene rubber (EPDM).

Other specific examples of the thermoplastic elastomer include olefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, and styrene-based thermoplastic elastomers. In particular, to reduce the weight of the upper body 10, an olefin-based thermoplastic elastomer is more preferable.

As illustrated in FIGS. 5 and 6, the stress relaxing portion 22 continues from a fixing position at which the upper body 10 and the upper midsole 5 are fixed together to an upper portion, of the upper body 10, in which the shoelace 16 is disposed. Specifically, a lower end of the stress relaxing portion 22 is fixed to a peripheral edge portion of the upper midsole component 5, while an upper end portion of the stress relaxing portion 22 is sewn to an upper peripheral portion of the upper body 10.

As illustrated in FIG. 5, before being pulled with the shoelace 16, the upper body 10 is loose and out of contact with the foot f of the wearer. In other words, before being pulled with the shoelace 16, the upper body 10 does not fit the foot f of the wearer.

On the other hand, as illustrated in FIG. 6, when the wearer laces the shoelace 16 and the upper body 10 is pulled with the shoelace 16 (hereinafter simply referred to as “the pulled state”), the stress relaxing portion 22 stretches in a direction from a base point that corresponds to a fixing position at which a lower portion of the upper body 10 and the sole body 2 are fixed together to the upper portion of the upper body 10. The stretch of the stress relaxing portion 22 makes the upper body 10 fit the foot f of the wearer.

When the shoelace 16 is loosened so that the upper body 10 is released from the pulled state, the stress relaxing portion 22 is restored to a state in which the stress relaxing portion 22 is loose and out of contact with the foot f of the wearer (see FIG. 5). In other words, the upper body 10 returns to a state in which it does not fit the foot f of the wearer.

FIG. 7 is a graph showing a how load varies with the passage of time while a predetermined amount of strain is maintained in a specimen of the stress relaxing member to which the load is applied. Specifically, FIG. 7 shows, in a case where a specimen of the stress relaxing member having a length of 30 mm and no fabric material 21 attached thereto is stretched at room temperature (23° C.) and at a tensile speed of 500%/s using a tensile tester (ElectroPuls E3000, manufactured by Instron Corporation) so that a load of 100 N is applied to the specimen, how the load applied to the stress relaxing member varies with the passage of time while the strain amount (5.7%) of the stress relaxing member is maintained. In FIG. 7, the horizontal axis represents time (s), and the vertical axis represents the load (N).

FIG. 7 shows that, in approximately 0.5 s since a load of approximately 100 N is applied to the specimen, the load applied to the specimen decreases to 10 N while the strain amount of the specimen is maintained at 5.7%. Then, from 0.5 s to 10 s, the load applied to the specimen gradually decreases to approximately 5 N while the strain amount is maintained at 5.7%.

The results shown in FIG. 7 demonstrate that in an elastic range, the stress relaxing member has such stress relaxation properties that the stress relaxing member relaxes, with the passage of time, the stress generated at the time of the application of a load, while remaining in a stretched state as described above. Specifically, in the elastic range, the stress relaxing portion 22 is configured to enter, when the upper body 10 is in the pulled state, the stretched state in which the stress relaxing portion 22 stretches to become longer than its initial length, and to relax the stress with the passage of time from the moment at which the upper body 10 enters the pulled state, while remaining in the stretched state.

Advantages of Embodiment

As described above, the stress relaxing portion 22 has stretchability and stress relaxation properties. Thanks to the stretchability of the stress relaxing portion 22, the upper body 10 including the stress relaxing portion 22 can be fitted to the shape and size of the foot f of each wearer, when pulled with the shoelace 16 (see FIG. 6). Such features allow fitting properties for conforming to differences in the shape and size of feet f among individual wearers to be exhibited. Further, the stress relaxation properties of the stress relaxing portion 22 can reduce the force with which the upper body 10 strongly tightens the foot f of the wearer due to the stress generated in the pulled state. As a result, even if the upper body 10 is fitted to the foot f of the wearer (see FIG. 6), the comfort is ensured. Thus, the upper structure 1 can improve the fitting properties for conforming to differences in the shape and size of feet f among various wearers, and can ensure the comfort.

Further, the upper body 10 is configured so that, when the upper body is released from the pulled state in which it pulled with the shoelace 16 and returns to a state before the pulled state, the stress relaxing portion 22 is restored to a state in which the stress relaxing portion 22 is loose and out of contact with the foot f of the wearer in the elastic range. As can be seen, since the stress relaxing portion 22 is elastically deformable and restorable, the upper body 10 can endure repeated use without losing shape.

On the other hand, the stress relaxing portion 22 continues from the fixing position at which a lower portion of the upper body 10 and the sole body 2 are fixed together to an upper portion of the upper body 10. In addition, the stress relaxing portion 22 is configured to stretch in the direction from the base point corresponding to the fixing positon to the upper portion of the upper body 10 when the upper body 10 is pulled with the shoelace 16. Hence, in the shoe S including the upper structure 1, the stress relaxing portion 22 stretches in a wide area from the fixing position of the upper body 10 and the sole body 2 to the upper portion of the upper body 10 to which the shoelace 16 is attached. Therefore, the upper body 10 can be easily fitted to the foot f of the wearer, providing improved comfort when the wearer wears the shoes S.

First Variation of Embodiment

In the above embodiment, the stress relaxing portion 22 is disposed so as to correspond to a portion, of the upper body 10, extending from the forefoot F to the hindfoot H of the foot f of the wearer. However, this is merely a non-limiting example. For example, as in a first variation illustrated in FIG. 8, the stress relaxing portion 22 may be disposed only in a portion, of the upper body 10, corresponding to the forefoot F of the foot f of the wearer. The first variation allows the upper body 10 to fit the forefoot F of the foot f of the wearer.

Second Variation of Embodiment

As in a second variation illustrated in FIG. 9, the stress relaxing portion 22 may be disposed only in a portion, of the upper body 10, corresponding to the midfoot M of the foot f of the wearer. The second variation allows the upper body 10 to fit the midfoot M of the foot f of the wearer.

Third Variation of Embodiment

As in a third variation illustrated in FIG. 10, the stress relaxing portion 22 may be disposed in a portion, of the upper body 10, corresponding to the forefoot F and the midfoot M of the foot f of the wearer. In addition, the upper body 10 is provided with a mesh portion 23. The mesh portion 23 is made of a mesh fabric material having, for example, a honeycomb pattern, and is fixed to the surface of the stress relaxing portion 22. This mesh portion 23 allows the stress relaxing portion 22 to further stretch, and to keep the stress relaxing portion 22 from stretching further than a predetermined stretched state. Note that the mesh shape of the mesh fabric is not limited to a honeycomb pattern as shown in FIG. 10, and various shapes can be adopted.

Fourth Variation of Embodiment

As in a fourth variation illustrated in FIG. 11, the stress relaxing portion 22 is disposed in a portion, of the upper body 10, corresponding to the forefoot F and the midfoot M of the foot f of the wearer. In addition, the upper body 10 is provided with reinforcement portions 24, 24, . . . Each reinforcement portion 24 is made of, for example, artificial leather, and is formed into the shape of a substantial strip extending in the vertical direction. The reinforcement portions 24, 24, . . . are spaced apart from each other in the longitudinal direction. Each reinforcement portion 24 has an upper end continuing to a lower portion of the eyelet trimming part 13, and a lower end fixed to the upper midsole component 5. The reinforcement portions 24, 24 . . . partially restrict stretch of the stress relaxing portion 22. This can make the wearer feel the foot f held more properly by the upper body 10.

Fifth Variation of Embodiment

Further, in the above embodiment, the stress relaxing portion 22 continues from the fixing position of the upper body 10 and the upper midsole component 5 to the position of the shoelace 16 inserted in the eyelet trimming part 13. However, this is merely a non-limiting example. For example, as in a fifth variation illustrated in FIG. 12, the stress relaxing portion 22 may be disposed in an intermediate portion in the vertical direction of the upper body 10.

As illustrated in FIG. 12, the stress relaxing portion 22 extends in the longitudinal direction so as to correspond a region from the forefoot F to the hindfoot H of the foot f of the wearer, and is formed in a substantially wavy shape in side view. Further, as illustrated in FIGS. 13 and 14, the stress relaxing portion 22 is fixed to a position corresponding to an intermediate portion in the vertical direction of the fabric material 21. Specifically, the stress relaxing portion 22 has an upper end fixed to a lower portion of the eyelet trimming part 13, and a lower end fixed to an upper portion of an exterior 25 provided to the upper midsole component 5.

Also in the upper structure 1 according to the fifth variation, the stretchability of the stress relaxing portion 22 above described allows the intermediate portion in the vertical direction of the upper body 10 to stretch when the upper body 10 is in the pulled state. Such a feature can improve fitting properties for conforming to differences in the shape and size of the feet f among the wearers. In addition, comfort can be ensured by the stress relaxation properties of the stress relaxing portion 22 described above.

Sixth Variation of Embodiment

As in a sixth variation illustrated in FIG. 15, the stress relaxing portion 22 may be disposed only in a portion, of the upper body 10, corresponding to the hindfoot H of the foot f of the wearer. This sixth variation allows the upper body 10 to fit the hindfoot H of the foot f of the wearer.

Further, as in the sixth variation, wires 26, 26 may be used as a fastening member together with the shoelace 16. When the upper body 10 is pulled forward with the shoelace 16 and the wires 26, 26, the stress relaxing portion 22 stretches in the longitudinal direction. Thus, the upper body 10 can be easily fitted to the hindfoot H (particularly, the heel) of the foot f of the wearer, so that the stability of the foot f of the wearer can be improved when the wearer steps on the ground during, for example, running or walking.

OTHER EMBODIMENTS

In the above embodiment, the shoelace 16 (the shoelace 16 and the wires 26, 26 in the sixth variation) is used as the fastening member. However, this is merely a non-limiting example. For example, instead of the shoelace 16, a belt (not shown) or a wire (not shown) may be used as a fastening member. Even if a belt or a wire is used as the fastening member, the same advantages as those of the above embodiment can be obtained.

In the embodiment described above, the stress relaxing member is fusion bonded to the fabric material 21 through hot pressing and cooling treatment. However, this is merely a non-limiting example. For example, the stress relaxing member may be fusion bonded to the surface of the fabric material 21 by injection molding.

Further, in the above embodiment, the stress relaxation member fusion bonded to the surface of the fabric material 21 is employed as the stress relaxing portion 22. However, this is merely a non-limiting example. For example, the stress relaxing member may be integrated with the fabric material 21 by adhesion with an adhesive, primer treatment, fixing by sewing, or any other means.

Alternatively, the stress relaxing portion may be integrated with the fabric material 21 by the following method: an extensible thermoplastic film (not shown) (i.e., a hot-melt adhesive) is applied to the back surface of the fabric material 21; and the stress relaxing member is bonded to the fabric material 21 via the thermoplastic film. This method makes it possible to bond the stress relaxing member to the fabric material 21, with the thermoplastic film separating the fabric material 21 from the stress relaxing member, while substantially preventing part of the thermoplastic elastomer (the stress relaxing member) from permeating the fabric material 21. Consequently, the fabric material 21 and the stress relaxing member can be firmly bonded to each other, while substantially preventing the upper body 10 from decreasing in stretchability.

In the embodiment described above, the stress relaxing portion 22 is formed on the surface of the fabric material 21, and the surface of the stress relaxing portion 22 is exposed to the outside. However, this is merely a non-limiting example. That is, as illustrated in FIG. 16, the fabric material 21 may be fixed to the surface of the stress relaxing portion 22 to keep the surface of the stress relaxing portion 22 from being exposed to the outside.

Note that the present disclosure is not limited to the embodiments described above, and various changes and modifications may be made without departing from the scope of the present disclosure.

The present disclosure is industrially applicable to, for example, athletic shoes for running and various sports, sneakers for daily use, and rehabilitation shoes. 

What is claimed is:
 1. An upper structure for a shoe, the upper structure comprising: an upper body including a stress relaxing portion which is elastically deformable; and a fastening member attached to the upper body, and configured to keep the upper body fitted to a foot of a wearer when the upper body is in a pulled state in which the upper body is pulled with the fastening member, wherein in an elastic range, the stress relaxing portion is configured to enter, when the upper body is in the pulled state, a stretched state in which the stress relaxing portion is stretched to become longer than an initial length thereof, and to relax stress with passage of time from a moment at which the upper body enters the pulled state, while remaining in the stretched state.
 2. The upper structure of claim 1, wherein the upper body is configured so that, when the upper body is released from the pulled state and returns to a state before the pulled state, the stress relaxing portion is restored to a state in which the stress relaxing portion is loose and out of contact with the foot of the wearer in the elastic range.
 3. The upper structure of claim 1, wherein the stress relaxing portion is disposed in a portion of the upper body, the portion corresponding to a forefoot of the foot of the wearer.
 4. The upper structure of claim 1, wherein the stress relaxing portion is disposed in a portion of the upper body, the portion corresponding to a midfoot of the foot of the wearer.
 5. The upper structure of claim 1, wherein the stress relaxing portion is disposed in a portion of the upper body, the portion corresponding to a hindfoot of the foot of the wearer.
 6. A shoe comprising the upper structure of claim
 1. 7. The shoe of claim 6, further comprising: a sole body configured to support the foot of the wearer and fixed to a lower portion of the upper body, wherein the fastening member is attached to an upper portion of the upper body, the stress relaxing portion continues from a fixing position at which the lower portion of the upper body and the sole body are fixed together to the upper portion of the upper body, and, is configured to stretch in a direction from a base point corresponding to the fixing position to the upper portion of the upper body when the upper body enters the pulled state.
 8. A shoe comprising the upper structure of claim 5, wherein the upper body is configured such that the stress relaxing portion stretches in a longitudinal direction while the upper body is pulled forward with the fastening member. 